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Calculating Absorptivity

I have tried to play with all the numbers in this question, but nothing seems to be working.

Nitrite ion, NO-2 is used as a preservative for bacon and other foods. It has been the center of controversy since it is potentially carcinogenic.

Here is an abbreviated procedure for the determination:

Step 1: 50.0 mL of unknown solution containing nitrite is added to 1.00 mL of sulfanic acid solution.
Step 2: After 10 min, 2.00 mL of 1-aminonaphthalene solution and 1.00 mL of buffer are added.
Step 3: After 15 min, the absorbance is read at 520 nm in a 5.00 cm cell.

The following solutions are analyzed:
A. 50.0 mL of food extract known to contain no nitrite (i.e a negligible amount); final absorbance =0.153
B 50.0 mL of food extract suspected of containing nitrite; final absorbance =0.622
C. Same as B, but with 10.0 mL of 7.50 x 10^-3 M NaNO2 added to the 50.0 mL sample; final absorbance =0.967

a) Calculate the molar absorptivity of the colored product. Remember that the cell is 5.00 cm.
b) How many micrograms of NO-2 were present in 50.0 ml of food extract.

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